The present invention relates to an apparatus and a method of receiving a broadcasted digital signal. More specifically, this invention relates to receiving a broadcasted digital signals with bit streams of digital data conveying packets under time-division multiplexing, each packet at least having a packet of program specific information of a large number of TV programs and packets of the TV programs themselves.
TV programs have been broadcasted in digital waveform via communications satellite. A digital TV signal conveys a composite signal of highly efficiently compressed digital data of a large number of TV programs under time-division multiplexing.
In the TV broadcasting, a large number of TV programs are highly efficiently compressed by an MPEG-2 encoder to be transformed into transport packets (TPs). Each TP has 188 megabyte-digital data. The TPs are merged into a composite signal by time-division multiplexing to be a transport stream (TS). The transport streams are transmitted in parallel via transponders, the number of the TSs being equal to that of the transponders.
Each TP has a packet of program specific information (PSI) of a large number of TV programs for audience's easier tuning to one of the large number of TV programs. This packet is called a PSI packet in the specification. And the PSI packet has packets of program association table (PAT), program map table (PMT), conditional association table (CAT) and network information table (NIT).
Digital TV broadcasting waves with bit streams of digital data with at least the PSI packet and packets of TV programs themselves under time-division multiplexing are transmitted to a digital TV broadcasting wave receiving apparatus, or a set top box (STB). The packets of TV programs themselves are called program packets in the specification. The STB is tuned to one of the large number of TV programs with reception of the PSI packet.
A conventional STB is shown in FIG. 1 with a tuner 1, a digital demodulator and error corrector 2, a system controller 3, a program data analyzer 4, a demultiplexer 5, a video and audio MPEG decoder 6, a selection data input terminal 7, an adder 8 and an antenna 9.
A digital broadcasting wave signal received via antenna 9 is amplified by the tuner 1 with frequency conversion. The digital signal is then fed to the digital demodulator and error corrector 2. The digital signal is demodulated with bit error correction.
The error-corrected bit stream of the digital signal is applied to the demultiplexer 5 and program data analyzer 4. The analyzer 4 analyzes PSI in the bit stream to find TV program titles. More in detail, after termination of PMT recognition processing to recognize PMTs corresponding to all TV programs indicated by the PAT, the titles are output from an output terminal 10 via adder 8 to be displayed on a screen (not shown).
An audience enters data for selecting one TV program via selection data input terminal 7. This data is fed to the system controller 3 to find the program packets only for the selected one TV program among the packets fed to the demultiplexer 5. The program packets are then fed to the decoder 6 from demultiplexer 5. The decoder 6 decodes digital data of video and audio packets. The decoded video and audio analog signals are then output from the output terminal 10 via adder 8.
As disclosed above, the conventional STB outputs video and audio analog signals of one specific TV program that an audience wants to watch among received TV programs. The video and audio analog signals of the specific TV program are recorded to and reproduced from a helical scanning type video cassette recorder (VCR) or a video tape recorder for analog video signals.
The inventors have devoted to recording bit streams of the selected and other several non-selected TV programs output by the digital demodulator and error corrector 2 using a D-VHS (trade mark) type VCR.
This VCR installs mechanism of the present helical scanning type S-VHS type VCR in order to be compatible with the S-VHS type VCR. Because the helical scanning type VCR can be used as a storage of large capacity of digital data. Further, the D-VSH type VCR can record and reproduce bit streams of digital data supplied via digital interface.
The D-VHS type VCR can record the PSI packet and program packets of several TV programs among the large number of TV programs. However, the conventional STB does not accept such a reproduced signal of the PSI packet and program packets of several TV programs.
Because as disclosed above, after termination of PMT recognition processing to recognize PMTs corresponding to all (the large number of) TV programs indicated by the PAT, the program data analyzer 4 finds the TV program titles that are output from the output terminal 10 via adder 8 to be displayed on a screen (not shown). In other words, the program data analyzer 4 requires program packets of not only several TV programs that an audience wants to record but also all (the large number of) TV programs indicated by the PAT.